Rotary electrical switches



Dec. 29, 1964 J. J. DRAGE 3,163,730

ROTARY ELECTRICAL SWITCHES Filed April 5, 1962 INVE/V TOR James John Droge ATTOR/VE 75 United States Patent Ofiice 3,163,736 Patented Dec. 29, 1954 This invention relates to rotary electrical switches and one of the objects of the invention is to provide a rotary electrical switch which is especially suitable for use in key-operated electronic calculating machines.

In a key-operated calculating machine the actuation of a key may cause contacts to be opened, closed, or changed over. in the known type of key-operated switch which has previously been used in electrical calculating machines it may happen th during the actuation of the key the con acts are closed opened a number of times for very short periods. Thus, for example, in a switch in which the contacts are closed on actuation of the key, it may lraupen that soon after the contacts have been closed during actuation they are opened again for a period of, for example, a few microseconds and are then reclosed. intervening opening of the contacts may be caused, for example, by a lateral component of pressure being applied by the operator during actuation of the key. Such short breaks in the continuity of the circuit have no effect in the case of electrical calculating machines having components with a comparatively slow response. However, in a calculating machine with electronic cour ing devices these devices may have a very short response time with the result thct errors are caused if a switch is opened even for only a few microseconds during the actuation of a key.

Accordingly it is a princi al object of the invention to provide a switch in which tee possibility of the contacts being inadvertently opened during actuation of a key is considerably reduced.

Preferably the key stem is mounted for linear movement in the direction of its longitudinal axis, whereas the bridge member is rotatable. The bridge member may, for example, be constituted by a rotatable plate of insulating material including a surface perpendicular to the axis of rotation. in case at least one portion of this surface is coated with conductive material which bridges the two, or two of the fixed contacts over a predetermined range of angular positions of the plate.

in a preferred form the switch includes three fixed contacts and in this case the rotatable plate has two portions of its surface facing the fixed contacts coated with conductive material. One of said portions bridges a first pair of the fixed contacts over a first range of angular positions of the plate and the other of said portions bridges a second pair of the fixed contacts over a second range of angular positions of the plate.

The coupling member is preferably in the form of an arm secured to the plate for rotation therewith and extending in a direction generally perpendicular to the axis of rotation of the plate to cooperate with a lug on the key stem. The arm may include a slot in which the lug on the key stem is freely movable in a direction parallel to the axis of rotation of the plate as well as in a direction perpendicular to the axis of rotation of the plate. The flexibility of the coupling arm should be so related to the strength of the spring means that, if the key stem is actuated in such a way as to apply a force to the coupling arm tending to move the coated surface of the plate out of engagement with the fixed contacts, the coupling arm will bend the electrical connection between the coated surface of the plate and the fixed contacts will not be broken.

this

Thus, from one asp ct the invention comprises in a rotary electrical switch including at least two fixed contacts, a rotatable plate of insulating material including a surface normal to the axis of rotation of the plate, spring means urging said surface in the direction of said fixed contacts, and actuating means for causing rotation of said plate, wherein said surface of the rotatable plate has at least one portion coated with conductive material capable of bridging said two, or two of said, fixed contacts over a predetermined range of angular positions of said plate.

Prom another aspect the invention comprises in a rotary electrical switch including at least two fixed contacts, a rotatable plate urged towards and co-operating with said fixed contacts, an operating member for said switch and means coupling said operating member to said plate to cause rotation of the plate on the actuation of the crating member, wherein said coupling means are flexible in a direction parallel to the axis of rotation of the plate.

From yet another aspect the invention comprises in a key-operated electrical switch including a key stein mounted for switch-operating movement in the direction of its longitudinal axis, at least two fixed contacts, a movable bridge member resiliently pressed against said fixed contacts operative to establish an electrical connection between said co cts in one gosition of said bridge member, and a resr ient coupling between said key stem and said bridge member.

From yet another aspect the invention comprises in a key-operated electrical switch including a key stern mounted for switch-operating movement in the direction of its longitudinal axis, three fixed contacts mounted on a base of insulating material, a plate of insulating material rotatable on a shaft secured to said base and having two portions of its surface facing said fixed contacts coated with conductive material, one of which portions bridges a first pair of the fixed contacts in a first angular position of said plate and the other of which portions bridges a second pair of the fixed contacts in a second angular position of the plate, spring mea s carried on said shaft and urging said coated surface of the plate towards said three fixed contacts, and a resilient coupling arm sec red to said plate for rotation therewith and extending in a direction generally perpendicular to the axis of said shaft to co-operate with 2. lug on said key stem.

Preferably said coupling arm consists of plastic or metal and is flexible in a first plane but substantially rigid in a second plane perpendicular to said first plane. The arm may include a slot in which lug on the key stem is freely movable in a direction parallel to the axis of the shaft. The flexibility of the coupling arm is so related to the strength of the spring means that, if the key stem is actuated in such a way as to apply a force to coupling arm ten ng to move the coated surface of the plate out of engagement with the fixed contacts, the coupling arm will bend the connection between the coated surface of the plate and the contacts will not be broken. Further, if the lateral displacement of the key stem is very large, slip will occur between the log and the coupling arm to reduce the pressure on the plate.

Que embodiment of the invention will now be do scribed with reference to the accompanying drawings in which:

FXGURE l is a rear view of the contact plate of a switch according to the invention,

FIGURE 2 is a side View of a switch according to the invention, and

FIGURE 3 illustrates the co-operation between the coupling arm of a switch according to the invention and a key stern.

Referring more particularly to FIGURES 1 and 2 it will be seen that the switch illustrated includes a plate of insulating material A having thereon two conductively coated areas All and A2 separated by a gap K. In the manufacture of the switch the plate A is first coated with copper and the gap K is etched away. Thereafter the areas A3 and A4 of the copper-coated plate are palladium-plated.

The switch plate A is rotatable on a spindle F riveted into a base board D of insulating material. Also riveted in the base board D are silver-graphite contacts B1, B2 and B3. The conductively-coated side of the plate A is urged towards the fixed contacts B1, B2 and B3 by a spring I held in position on the spindle F by a washer G and a circlip H.

An aperture L is provided in the plate A and into this aperture a boss E on a nylon actuator arm M fits. A slot M1 is formed in the arm M, and, as can be seen from FIGURE 3, a lug N1 on a key stem N fits into this slot. The key stem N is movable in the direction of its longitudinal axis by manual pressure on a key N2. Means are provided for guiding the key stem during this movement and spring means are provided to cause the key stem to return to its normal position when pressure on the key is removed.

The switch is shown in its normal position in FIGURE 3 and when the key is depressed the plate A is displaced into the position illustrated in FIGURE 1. In this way, when the key is actuated, the contact B1 is connected to the contact B2 through the palladium coating A3, but the contact B3 is not connected to either of the other two contacts. When the key is released the plate A is rotated in a clockwise direction, as seen in FIGURE 1, so that the palladium coating A3 is moved out of engagement with the contact B1 and the palladium coating A4- is moved into engagement with the contact B1. The contact B2 remains in engagement with the coating A3 and the contact B3 remains in engagement with the coating A4. As a result the contacts B1 and B3 are interconnected whilst the contact B2 is disconnected.

Since the arm M is made of flexible material, a small lateral displacement of the key stem N in a plane perpendicular to the plane of the plate A will merely cause the arm to bend and will not affect the connection between the operat-ive palladium coating and the respective contacts. If the displacement in this plane is large enough, it may even happen that the arm slips on the lug N1. It will be appreciated that it would not be sufficient merely to provide for slip between these two elements since displacement of the plate A might well occur for a short period before relative movement between the arm and the key stem had started.

Lateral displacement of the key stem in a plane parallel to the plane of the plate A will cause the lug N1 to slide along the slot M1.

It will be seen from FIGURE 2 that the outer periphery of the upper surface of the nylon arm M is provided with a substantially semicircular upstanding portion to retain the spring I. In addition this arm is provided with an upstanding boss M2, which can be seen in both FIGURES 2 and 3, to prevent the spring from moving in the direction of the slot Ml. Further, the arm M is provided with two protrusions M3 and M4 extending from the opposite side of the arm to the boss M2. These protrusions are visible in FIGURE 1 and serve to strengthen the arm in the vicinity of engagement between the arm and the lug N1.

As an additional protection against unwanted operation of the switch as a result of vibration the base board D is preferably mounted resiliently in the chassis of the machine in which the switch is incorporated. This resilient mounting may, for example, be provided by means of short rubber spindles projecting in both directions through holes provided in the base board.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A key-operated electrical switch comprising a base of insulating material, at least two fixed contacts mounted on said base, a shaft fixed to and projecting perpendicularly from said base, a contact plate rotatable on said shaft and cooperating with said fixed contacts, spring means carried on said shaft and urging said plate along said shaft towards said fixed contacts, a flexibly resilient coupling arm secured to said plate for rotation therewith on said shaft and provided with a slot extending in a direction generally perpendicular to the axis of said shaft, and a key stem mounted for movement in the direction of its longitudinal axis and provided with an operating lug slidable in said slot.

2. A switch in accordance with claim 1, wherein at least one portion of a surface of said rotatable plate perpendicular to said shaft is coated with conductive material, the conductive material bridging the fixed con tacts over a predetermined range of angular positions of the plate.

3. A key-operated electrical switch comprising a key stem mounted for switch-operating movement in the direction of its longitudinal axis, a base of insulating material, three fixed contacts mounted on said base, a shaft secured to and projecting from said base, a plate of insulating material rotatably mounted on said shaft, said plate having first and second portions of its surface facing said fixed contacts coated with conductive material, said conductive material coated on said first portion extending to bridge a first pair of said fixed contacts in a first angular position of said plate and said conductive material coated on said second portion extending to bridge a second pair of said fixed contacts in a second angular position of said plate, said key-operated switch further comprising spring means carried on said shaft for urging said coated surface of said plate towards said three fixed contacts, and a flexibly resilient coupling arm secured to said plate for rotation therewith on said shaft, said coupling arm having an extension in a direction generally perpendicular to the axis of said shaft, said extension engaging said key stem whereby reciprocating movement of said key stem in the direction of its longitudinal axis causes rotational movement of said plate between said first and second angular positions thereof.

4. A switch in accordance with claim 3 wherein said coupling arm is provided with a slot' and said key stem is provided with a lug, said lug being slidably engaged in said slot.

5. A key-operated electrical switch comprising a base of insulating material, at least two fixed contacts mounted on said base, a shaft fixed to and projecting perpendicularly from said base, a contact plate rotatably mounted on said shaft and cooperating with said fixed contacts, s ring means carried on said shaft and urging said plate along said shaft towards said fixed contacts, a flexibly resilient coupling arm secured to said plate for rotation therewith on said shaft, said coupling arm being pro vided with a slot extending in a direction generally perpendicular to the axis of said shaft and strengthening members substantially perpendicular to the sides of said slot and extending from said arm substantially parallel to said shaft, said electrical switch further comprising a key stem mounted for movement in the direction of its longitudinal axis and provided with an operating lug for engagement in said slot in the vicinity of said strengthening members.

6. A key-operated electrical switch comprising a base of insulating material, three fixed contacts mounted on said base, a shaft fixed to and projecting perpendicularly from said base, a contact plate rotatably mounted on said shaft and having each of two portions of its surface facing said fixed contacts coated with a planar layer of conductive material, said conductive material coated on a first of said two portions extending to bridge a first pair of'said fixed contacts in a first angular position of said plate and said conductive material coated on a secend of said two portions extending to bridge a second pair of fixed contacts in a second angular position of said plate, said key-operated switch further comprising spring means carried on said shaft for urging said coated surface of said plate towards said three fixed contacts, and a flexibly resilient coupling arm secured to said plate for rotation therewith on said shaft, said coupling arm having an extension in a direction generally perpendicular to the axis of said shaft, said extension engaging said key stem whereby reciprocating movement of said key stem in the direction of its longitudinal axis causes rotational movement of said plate between said first and second angular positions thereof.

7. A key-operated electrical switch comprising a key stem having a substantial longitudinal extension, mounting means for said key stem disposed nearer one end of said stem than the other end thereof, said key stem being movable with respect to said mounting means in the direction of the longitudinal axis of said key stern, said switch further comprising 3, lug coupled to said key stem near the end thereof remote from said mounting means, a base of insulating material mounted in fixed relation with respect to said key stem mounting means, three fixed contacts mounted on said base, a shaft secured to and projecting perpendicularly from said base, a coupling member rotatably mounted on said shaft, said coupling member comprising a flexibly resilient actuator arm and a boss coupled to said actuator arm, said boss and said actuator arm having aligned apertures for rotatably mounting said coupling member on said shaft, said boss extending along said shaft towards said base of insulating material, said actuator arm having an extension in a direction generally perpendicular to the axis of said shaft and a slot in said extension of said arm, said slot engaging said lug on said key stem, said electrical switch still further comprising a bridge member rotatably mounted on said shaft, said bridge member comprising an apertured plate of insulating material including a substantially flat surface perpendicular to said shaft and facing said fixed contacts, said boss on said coupling member interfitting with the aperture through said plate so as to secure said plate to said coupling member for rotation therewith, said bridge member further comprising first and second strips of electrically conductive material, coated, respcctively, on first and second portions of said surface of said plate, said first strip of conductive material extending along said surface to bridge a first pair of said fixed contacts in a first angular position of said plate and said second strip of conductive material extending along said surface to bridge a second pair of fixed contacts in a second angular position of said plate, whereby longitudinal movement of said key stem causes rotational movement of said bridge member between its first and second angular positions and movement of said key stem perpendicular to its longitudinal axis causes flexing of said actuator arm.

Hill May 19, 1942 Elliott June 26, 1962 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3 168,73O December 29 1964 James John Drage It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 20, before "fixed" insert said Signed and sealed this 4th day of May 1965:

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aitesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 163,730 December 29 1964 James John Drage It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 20, before "fixed" insert said Signed and sealed this 4th day of May 1965:

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altesting Officer Commissioner of Patents 

1. A KEY-OPERATED ELECTRICAL SWITCH COMPRISING A BASE OF INSULATING MATERIAL, AT LEAST TWO FIXED CONTACTS MOUNTED ON SAID BASE, A SHAFT FIXED TO AND PROJECTING PERPENDICULARLY FROM SAID BASE, A CONTACT PLATE ROTATABLE ON SAID SHAFT AND COOPERATING WITH SAID FIXED CONTACTS, SPRING MEANS CARRIED ON SAID SHAFT AND URGING SAID PLATE ALONG SAID SHAFT TOWARDS SAID FIXED CONTACTS, A FLEXIBLY RESILIENT COUPLING ARM SECURED TO SAID PLATE FOR ROTATION THEREWITH ON SAID SHAFT AND PROVIDED WITH A SLOT EXTENDING IN A DIRECTION GENERALLY PERPENDICULAR TO THE AXIS OF SAID SHAFT, AND A KEY STEM MOUNTED FOR MOVEMENT IN THE DIRECTION OF ITS LONGITUDINAL AXIS AND PROVIDED WITH AN OPERATING LUG SLIDABLE IN SAID SLOT. 